The transition from elementary to middle school entails increased likelihood of health risk behaviors including aggression/violence, depression, substance use, and school disengagement/failure. This study proposes to rigorously test the effects of a long-term (3-year), school-randomized universal preventive intervention called 4Rs (Reading, Writing, Respect and Resolution) on children's health risk behaviors as they make the transition from elementary to middle school. Specifically, the proposed study will: (1) test whether 4Rs produces changes in children's aggression/violence, depression, substance use, and school disengagement/failure over the transition from elementary to middle school;(2) examine the specific causal processes by which the preventive intervention affects children's health risk behaviors in middle school;(3) test differential effects of 4Rs on children's health risk behaviors for subgroups of "developmentally vulnerable" and "ecologically vulnerable" children as well as for girls and boys;and (4) conduct three additional exploratory sets of analyses to (a) examine issues of comorbidity among the four domains using dynamic, continuous latent class modeling, (b) explore the impact of two important micro-context mediators of 4R's long-term impact operationalized at the classroom-level including the peer ecology and classroom climate, and (c) use propensity score techniques to test the sensitivity of the results after accounting for any take-up of the intervention in the control schools. The 4Rs Program is a whole-school intervention that integrates violence prevention and social and emotional learning strategies into the language arts curriculum for grades K-5, providing a pedagogical link between teaching conflict resolution and fundamental academic skills. In a prior rigorous evaluation, an earlier version of this intervention demonstrated promising results in altering children's trajectories of aggression- related cognitions and beliefs, behavioral dispositions and interpersonal relationships, aggressive/violent behavior, and academic achievement over the course of elementary school. The current study proposes to continue to follow over 800 children in 18 New York City elementary schools (9 of which were randomly assigned to receive 4Rs) from the end of elementary school through the final year of middle school. We estimate that the children will move to over 100 middle schools throughout New York City. By testing the effects of a long-term intervention delivered in elementary school on children's subsequent transition to middle school, this study hopes to make new contributions to intervention theory and understanding of the onset, developmental course, and mediating causal process in several key domains of health risk behaviors. Results will be proactively disseminated to local and national public health, criminal justice, substance use prevention and mental health-related audiences. PUBLIC HEALTH RELEVANCE: The transition from elementary to middle school is fraught with both opportunity and danger, especially for low-income children of color in urban schools. On average, rates of health risk behaviors (e.g., violence/aggression and delinquency, depression, substance use, and academic failure) increase during the late elementary and early adolescent years putting children and youth at greater risk for poor future functioning. This project capitalizes on a random assignment study of a universal school-based violence prevention and literacy instruction program to examine (1) the nature and developmental path of several primary health risk behaviors from childhood through early adolescence, (2) the degree to which these risk behaviors are modifiable by a universal preventive intervention in elementary school, and (3) the important process by which the intervention has its impact.